Vibratory Finishing of Rigid PolyJet Parts

POLYJET BEST PRACTICE
Vibratory Finishing of
Rigid PolyJet Parts
SOFTWARE / PRODUCT / FINISHING
Overview
Polishing PolyJet™ 3D Printed parts in a vibratory finishing system (also
known as a tumbler) improves their surface finish by removing minor surface
irregularities and sharp edges. With this process you can save time and manual
labor, especially when dealing with large quantities or complex models. A tumbler
system can polish multiple parts, hands-free, in only a few hours, depending on
the size of the parts and the tumbler. This method is usually performed on metal
parts, but it was tested on PolyJet models from the Digital ABS™ and Vero™
material families and found suitable.
The System
The tumbler system is a combination of several elements. The main component is
the vibrator, which is usually a round tub or bowl with a vibrating rod in the center.
The rod increases the tumbler’s working strength and reduces part collisions.
Figure 1: Different shapes of ceramic media.
Parts are inserted into the tumbler filled with abrasive material, which is then
rotated. As the tumbler revolves, the abrasive materials mix around the parts
creating a circulation inside the tumbler. The moving contact between the parts
and the abrasive materials achieves the polishing action. The vibration rate can be
modified manually according to the delicacy of the models.
Vibrator sizes vary from about 25 liters (approximately 1100 mm [43 in.] diameter),
suitable for several small parts, to 100 liters (approximately 2000 mm [79 in.]
diameter), appropriate for a large number of small parts or several large parts. A
large vibrator can be also divided into smaller chambers to separate groups of
parts or to use a different abrasive material.
Stratasys has tested and recommends the TAMEX-ZLZ series vibrators from
Dalian Yincheng Polishing Equipment Company. Work with the vendor to choose
the right size system for your typical part.
THE 3D PRINTING SOLUTIONS COMPANY ™
VIBRATORY FINISHING OF RIGID POLYJET PARTS
In addition to the vibrator, a dosage unit is needed to control the amount of liquid
compound (one of the materials used in the finishing process) inserted during the
operation, with a flow meter that operates an automatic tap.
1.Options
Abrasive Media and Fluid Compounds
Abrasive media is available in a variety of materials and shapes, and using a
mixture of them provides the best results. Other materials and solutions may
be used with the abrasive media for lubrication, cleaning and other purposes.
Stratasys testing included the following three materials:
Figure 2: PolyJet parts inside a round tumbler covered with
powder compound.
1. Media – Abrasive media is made from materials such as sand, granite
chips, glass, ceramics and synthetics in a wide variety of shapes. Each
achieves a different surface finish.
Consider the size and geometry of your most-used parts when choosing
media. Small parts require small media, and highly detailed parts or parts
with fine features require complex media shapes such as star or triangle.
Be aware that manufacturer finish descriptions such as “brushed” or
“satin” describe results for metal parts, not PolyJet materials.
Stratasys has tested ceramic media types RS14/05E and RSD 10/10DZS
from Rosler (www.rosler.com).
2. Liquid Compound – Liquid compounds form the foundation of the
surface finishing process. They remove contaminants such as model
debris and ensure that the media perform properly. They also provide
lubrication to the entire process.
Stratasys has tested liquid compound type FC 1236 from Rosler.
3. Powder Compounds – Powder compounds are similar to liquid
compounds in that they also help facilitate the finishing process by
degreasing, etching, cleaning and enhancing the cutting performance of
the abrasive media.
Figure 3: PolyJet parts inside a round tumbler with
ceramic media.
Stratasys has tested powder compounds type RSP 506S from Rosler.
2.Process
When your parts have achieved the desired surface finish, pour water into the
tumbler for several minutes to wash residue left on the parts before removing
them. If the parts have some narrow slots or if an additional delicate polish is
needed, add dish soap to the tumbler for about 10 minutes.
Results may vary depending on the specific PolyJet material being finished,
the type of media used and the time spent in the tumbler. Performing a test to
determine the best combination of finish parameters for your particular material
is recommended.
POLYJET BEST PRACTICE / 2
VIBRATORY FINISHING OF RIGID POLYJET PARTS
Regardless of the abrasive material being used, it is important to remove the
parts from the system at the end of the finishing process to prevent sediment
from collecting on them. Don’t allow parts to dwell in stationary media. Rinse
parts in clean water to remove any residue.
3.Safety
Observe manufacturer’s recommendations for safety, material handling
and storage. This information can be found in the safety data sheet for
each material.
4. Tools And Supplies
4.1.Equipment:
•Mass finishing vibratory system
•Compound dosing system
4.2.Media
4.3.Fluid compound
POLYJET BEST PRACTICE / 3
VIBRATORY FINISHING OF RIGID POLYJET PARTS
CONTACT
For questions about the information contained in this document,
contact Stratasys at www.stratasys.com/contact-us/contact-stratasys.
E info@stratasys.com / S T R ATA SYS .C O M
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